The present invention relates to surgical instruments for use in ophthalmic surgery and, in particular, to aspiration-irrigation devices utilized for cataract surgery.
During cataract surgery, various parts of the eye, including the lens, are removed and/or the clouded lens is ultrasonically pulverized and then removed. Many techniques have been conventionally utilized to remove various parts of the eye in conjunction with the lens. For example, a conventional aspiration-irrigation device has been used for a number of years in both planned extracapsular surgery and for cortical cleanup after Phachoemulsification techniques. Such devices often include an inner and outer cannula cooperating with a source of irrigating fluid and-with a vacuum or suction developing source. The inner cannula reciprocates within the outer cannula and includes a port on the end which is connected through an inner lumen with the vacuum source.
Irrigating fluid is allowed to flow between the inner and outer cannulas so as to irrigate the eye during utilization of the device. In various devices, the irrigating fluid may flow through and out the end of the outer cannula or may flow through ports in the sides of the outer cannula. The vacuum is selectively controlled by the surgeon to allow only the material which is desired to be removed to be withdrawn from the eye. The conventional aspiration-irrigation devices have been frequently used to remove cortical material from the posterior capsule. In general, the cortical material is drawn into the port of the interior cannula and a vacuum is applied to hold it there. The device is then maneuvered such that the cortical material is pulled away from the posterior capsule without tearing or rupturing the capsule, and the material is pulled into the interior cannula to be drawn therethrough by suction selectively applied by the surgeon.
Such techniques are somewhat effective on the cortical material which is easily drawn into the port of the inner cannula and thereafter through the inner cannula by the selectively applied suction. However, there are often fragments of other parts of the eye which should be removed during the surgery, but which are not as easily loosened from the eye as is the cortical material. For example, a piece or tag of the anterior capsule may remain after a standard serration cutting, sometimes referred to as "beer can opener", cutting and removal of the anterior capsule. In the past, one process, referred to as the the Kelman "toilet-tissue" technique, has been utilized for removing such a tag. In this technique, the tag is grasped by intraocular irrigating forceps and briskly snapped. This technique often adequately removes the tag, but in some situations the zonules are broken.
Another technique used for removing anterior capsule fragments has been to utilize an aspiration-irrigation device in conjunction with a Franceschetti hook. In this technique, the fragment is sucked against the port on the interior cannula, while the hook is inserted into the port so as to firmly grasp the fragment. The hook, while still in the port, is then pulled radially inward toward the central axis of the eye to tear the fragment. This technique can produce unintended tearing and does not cleanly remove the anterior capsule fragments.
It is often desirable during eye surgery to remove various fragments or filaments from within the eye which are attached to some other structure and are not easily removed by tugging or tearing, without damaging the structure to which it is attached or a surrounding structure.